The quantitative determination of analytes in body fluids is of great importance in the diagnoses and maintenance of certain physiological abnormalities. For example, lactate, cholesterol and bilirubin should be monitored in certain individuals. In particular, it is important to diabetic individuals to frequently check the glucose level in their body fluids to regulate the glucose intake in their diets. The results of such tests can be used to determine what, if any, insulin or other medication needs to be administered. In one type of blood-glucose testing system, sensors are used to test a sample of blood.
A test sensor contains biosensing or reagent material that reacts with blood glucose. The testing end of the sensor is adapted to be placed into the fluid being tested, for example, blood that has accumulated on a person's finger after the finger has been pricked. The fluid is drawn into a capillary channel that extends in the sensor from the testing end to the reagent material by capillary action so that a sufficient amount of fluid to be tested is drawn into the sensor. The fluid then chemically reacts with the reagent material in the sensor resulting in an electrical signal indicative of the glucose level in the fluid being tested. This signal is supplied to the meter via contact areas located near the rear or contact end of the sensor and becomes the measured output.
A problem occurs when the test sensor is to be modified such as, for example, a modification in the reagent material. During the time period before the modified test sensor is to be launched, there exists significant inventory of existing test sensors. In the past, the manufacturer may have delayed launching the new modified test sensor until the existing test sensors were purged from the marketplace. One disadvantage of such a process is that the new system using the new modified test sensor cannot be realistically marketed until after it is in place. Another option for the manufacturer would be to swap the existing test sensors after the launch of the modified test sensor. This has the disadvantage of being costly since there are costs associated with removing existing product from the marketplace as well as opportunities lost if the existing test sensors cannot be used.
It would be desirable to provide a test sensor that would avoid the need to delay launch of a modified test sensor without the need to swap out the existing test sensor with the modified test sensor.